(a) Field of the Invention
The present invention relates to analytical procedures regarding vaporization of materials by laser from a surface, and in particular, a probe for interrogation of laser-generated plumes having a density gradient.
(b) Problems in the Art
The imposition of an energy source, such as a laser beam, to a surface, with subsequent vaporization of a material on the surface, is of active interest for analytical purposes. The vaporized material forms what is called a plume, which generally expands and travels upwardly and away from the surface.
There are a number of techniques which can be used to analyze the plume of vaporized material. Some of these techniques are optical spectroscopy, mass spectroscopy, and interferometry.
These techniques are generally acceptable, but have shortcomings. Particularly with respect to use of a laser to generate the plume, these techniques are deficient in that they are not able to or are imprecise in deriving information about what occurs at the surface, and what occurs shortly after generation of the plume. Additionally, the results are unreliable. Some of the unreliability involves the inherent pulse fluctuations of laser beams, and varying surface properties of materials.
The benefit of more precise and reliable interrogation and derivation of information is important with respect to analysis of the surface and the vaporized materials, and can be helpful in analyzing material processing. One example would be the direct hard wiring of semiconductor devices.
Certain attempts have been made to improve over conventional methods. However, while some of these methods function adequately in certain situations, but not in others.
There is therefore a real need in the art for a universal probe which can be utilized in all different types of relevant situations.
It is therefore a principal object of the present invention to provide a method and means for a spatial and temporal probe for laser-generated plumes based on density gradients which improves over or solves the problems and deficiencies in the art.
A further object of the present invention is to provide a means and method as above described which is more precise and more sensitive than current techniques.
A further object of the present invention is to provide a means and method as above described which is useful in many types of interrogation of laser generated plumes.
Another object of the present invention is to provide a means and method as above described which provides correlated information regarding space and time with respect to the plume.
A further object of the present invention is to provide a means and method as above described which is efficient, economical, and accurate.
These and other objects, features, and advantages of the present invention will become more apparent with reference to the accompanying specification and claims.